A series of cyclometalated platinum(II) complexes of the type [(ppy)Pt(L-M)](n+) (n = 0, 1) with p-bonded catecholates acting as organometallic ligands (L-M) have been prepared and characterized by analytical techniques. In addition, the structures of two complexes of the series were determined by single-crystal X-ray diffraction. The packing shows the formation of a 1D supramolecular assembly generated by d(Pt)-pi C-p* interactions among individual units. All complexes are luminescent in the solid state and in solution media. The results of photophysics have been rationalized by means of density functional theory (DFT) and time-dependent DFT investigations.